[resend PATCH v2 15/33] filesystem-dax: convert to dax_direct_access()

From: Dan Williams
Date: Mon Apr 17 2017 - 15:16:07 EST

Now that a dax_device is plumbed through all dax-capable drivers we can
switch from block_device_operations to dax_operations for invoking
->direct_access.

This also lets us kill off some usages of struct blk_dax_ctl on the way
to its eventual removal.

Suggested-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
---
fs/dax.c | 277 +++++++++++++++++++++++++++++----------------------
fs/iomap.c | 3 -
include/linux/dax.h | 6 +
3 files changed, 162 insertions(+), 124 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index b78a6947c4f5..ce9dc9c3e829 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -55,32 +55,6 @@ static int __init init_dax_wait_table(void)
}
fs_initcall(init_dax_wait_table);

-static long dax_map_atomic(struct block_device *bdev, struct blk_dax_ctl *dax)
-{
- struct request_queue *q = bdev->bd_queue;
- long rc = -EIO;
-
- dax->addr = ERR_PTR(-EIO);
- if (blk_queue_enter(q, true) != 0)
- return rc;
-
- rc = bdev_direct_access(bdev, dax);
- if (rc < 0) {
- dax->addr = ERR_PTR(rc);
- blk_queue_exit(q);
- return rc;
- }
- return rc;
-}
-
-static void dax_unmap_atomic(struct block_device *bdev,
- const struct blk_dax_ctl *dax)
-{
- if (IS_ERR(dax->addr))
- return;
- blk_queue_exit(bdev->bd_queue);
-}
-
static int dax_is_pmd_entry(void *entry)
{
return (unsigned long)entry & RADIX_DAX_PMD;
@@ -553,21 +527,30 @@ static int dax_load_hole(struct address_space *mapping, void **entry,
return ret;
}

-static int copy_user_dax(struct block_device *bdev, sector_t sector, size_t size,
- struct page *to, unsigned long vaddr)
+static int copy_user_dax(struct block_device *bdev, struct dax_device *dax_dev,
+ sector_t sector, size_t size, struct page *to,
+ unsigned long vaddr)
{
- struct blk_dax_ctl dax = {
- .sector = sector,
- .size = size,
- };
- void *vto;
-
- if (dax_map_atomic(bdev, &dax) < 0)
- return PTR_ERR(dax.addr);
+ void *vto, *kaddr;
+ pgoff_t pgoff;
+ pfn_t pfn;
+ long rc;
+ int id;
+
+ rc = bdev_dax_pgoff(bdev, sector, size, &pgoff);
+ if (rc)
+ return rc;
+
+ id = dax_read_lock();
+ rc = dax_direct_access(dax_dev, pgoff, PHYS_PFN(size), &kaddr, &pfn);
+ if (rc < 0) {
+ dax_read_unlock(id);
+ return rc;
+ }
vto = kmap_atomic(to);
- copy_user_page(vto, (void __force *)dax.addr, vaddr, to);
+ copy_user_page(vto, (void __force *)kaddr, vaddr, to);
kunmap_atomic(vto);
- dax_unmap_atomic(bdev, &dax);
+ dax_read_unlock(id);
return 0;
}

@@ -735,12 +718,16 @@ static void dax_mapping_entry_mkclean(struct address_space *mapping,
}

static int dax_writeback_one(struct block_device *bdev,
- struct address_space *mapping, pgoff_t index, void *entry)
+ struct dax_device *dax_dev, struct address_space *mapping,
+ pgoff_t index, void *entry)
{
struct radix_tree_root *page_tree = &mapping->page_tree;
- struct blk_dax_ctl dax;
- void *entry2, **slot;
- int ret = 0;
+ void *entry2, **slot, *kaddr;
+ long ret = 0, id;
+ sector_t sector;
+ pgoff_t pgoff;
+ size_t size;
+ pfn_t pfn;

/*
* A page got tagged dirty in DAX mapping? Something is seriously
@@ -789,26 +776,29 @@ static int dax_writeback_one(struct block_device *bdev,
* 'entry'. This allows us to flush for PMD_SIZE and not have to
* worry about partial PMD writebacks.
*/
- dax.sector = dax_radix_sector(entry);
- dax.size = PAGE_SIZE << dax_radix_order(entry);
+ sector = dax_radix_sector(entry);
+ size = PAGE_SIZE << dax_radix_order(entry);
+
+ id = dax_read_lock();
+ ret = bdev_dax_pgoff(bdev, sector, size, &pgoff);
+ if (ret)
+ goto dax_unlock;

/*
- * We cannot hold tree_lock while calling dax_map_atomic() because it
- * eventually calls cond_resched().
+ * dax_direct_access() may sleep, so cannot hold tree_lock over
+ * its invocation.
*/
- ret = dax_map_atomic(bdev, &dax);
- if (ret < 0) {
- put_locked_mapping_entry(mapping, index, entry);
- return ret;
- }
+ ret = dax_direct_access(dax_dev, pgoff, size / PAGE_SIZE, &kaddr, &pfn);
+ if (ret < 0)
+ goto dax_unlock;

- if (WARN_ON_ONCE(ret < dax.size)) {
+ if (WARN_ON_ONCE(ret < size / PAGE_SIZE)) {
ret = -EIO;
- goto unmap;
+ goto dax_unlock;
}

- dax_mapping_entry_mkclean(mapping, index, pfn_t_to_pfn(dax.pfn));
- wb_cache_pmem(dax.addr, dax.size);
+ dax_mapping_entry_mkclean(mapping, index, pfn_t_to_pfn(pfn));
+ wb_cache_pmem(kaddr, size);
/*
* After we have flushed the cache, we can clear the dirty tag. There
* cannot be new dirty data in the pfn after the flush has completed as
@@ -818,8 +808,8 @@ static int dax_writeback_one(struct block_device *bdev,
spin_lock_irq(&mapping->tree_lock);
radix_tree_tag_clear(page_tree, index, PAGECACHE_TAG_DIRTY);
spin_unlock_irq(&mapping->tree_lock);
- unmap:
- dax_unmap_atomic(bdev, &dax);
+ dax_unlock:
+ dax_read_unlock(id);
put_locked_mapping_entry(mapping, index, entry);
return ret;

@@ -840,6 +830,7 @@ int dax_writeback_mapping_range(struct address_space *mapping,
struct inode *inode = mapping->host;
pgoff_t start_index, end_index;
pgoff_t indices[PAGEVEC_SIZE];
+ struct dax_device *dax_dev;
struct pagevec pvec;
bool done = false;
int i, ret = 0;
@@ -850,6 +841,10 @@ int dax_writeback_mapping_range(struct address_space *mapping,
if (!mapping->nrexceptional || wbc->sync_mode != WB_SYNC_ALL)
return 0;

+ dax_dev = dax_get_by_host(bdev->bd_disk->disk_name);
+ if (!dax_dev)
+ return -EIO;
+
start_index = wbc->range_start >> PAGE_SHIFT;
end_index = wbc->range_end >> PAGE_SHIFT;

@@ -870,38 +865,49 @@ int dax_writeback_mapping_range(struct address_space *mapping,
break;
}

- ret = dax_writeback_one(bdev, mapping, indices[i],
- pvec.pages[i]);
- if (ret < 0)
+ ret = dax_writeback_one(bdev, dax_dev, mapping,
+ indices[i], pvec.pages[i]);
+ if (ret < 0) {
+ put_dax(dax_dev);
return ret;
+ }
}
}
+ put_dax(dax_dev);
return 0;
}
EXPORT_SYMBOL_GPL(dax_writeback_mapping_range);

static int dax_insert_mapping(struct address_space *mapping,
- struct block_device *bdev, sector_t sector, size_t size,
- void **entryp, struct vm_area_struct *vma, struct vm_fault *vmf)
+ struct block_device *bdev, struct dax_device *dax_dev,
+ sector_t sector, size_t size, void **entryp,
+ struct vm_area_struct *vma, struct vm_fault *vmf)
{
unsigned long vaddr = vmf->address;
- struct blk_dax_ctl dax = {
- .sector = sector,
- .size = size,
- };
- void *ret;
void *entry = *entryp;
+ void *ret, *kaddr;
+ pgoff_t pgoff;
+ int id, rc;
+ pfn_t pfn;

- if (dax_map_atomic(bdev, &dax) < 0)
- return PTR_ERR(dax.addr);
- dax_unmap_atomic(bdev, &dax);
+ rc = bdev_dax_pgoff(bdev, sector, size, &pgoff);
+ if (rc)
+ return rc;

- ret = dax_insert_mapping_entry(mapping, vmf, entry, dax.sector, 0);
+ id = dax_read_lock();
+ rc = dax_direct_access(dax_dev, pgoff, PHYS_PFN(size), &kaddr, &pfn);
+ if (rc < 0) {
+ dax_read_unlock(id);
+ return rc;
+ }
+ dax_read_unlock(id);
+
+ ret = dax_insert_mapping_entry(mapping, vmf, entry, sector, 0);
if (IS_ERR(ret))
return PTR_ERR(ret);
*entryp = ret;

- return vm_insert_mixed(vma, vaddr, dax.pfn);
+ return vm_insert_mixed(vma, vaddr, pfn);
}

/**
@@ -950,24 +956,34 @@ static bool dax_range_is_aligned(struct block_device *bdev,
return true;
}

-int __dax_zero_page_range(struct block_device *bdev, sector_t sector,
- unsigned int offset, unsigned int length)
+int __dax_zero_page_range(struct block_device *bdev,
+ struct dax_device *dax_dev, sector_t sector,
+ unsigned int offset, unsigned int size)
{
- struct blk_dax_ctl dax = {
- .sector = sector,
- .size = PAGE_SIZE,
- };
-
- if (dax_range_is_aligned(bdev, offset, length)) {
- sector_t start_sector = dax.sector + (offset >> 9);
+ if (dax_range_is_aligned(bdev, offset, size)) {
+ sector_t start_sector = sector + (offset >> 9);

return blkdev_issue_zeroout(bdev, start_sector,
- length >> 9, GFP_NOFS, true);
+ size >> 9, GFP_NOFS, true);
} else {
- if (dax_map_atomic(bdev, &dax) < 0)
- return PTR_ERR(dax.addr);
- clear_pmem(dax.addr + offset, length);
- dax_unmap_atomic(bdev, &dax);
+ pgoff_t pgoff;
+ long rc, id;
+ void *kaddr;
+ pfn_t pfn;
+
+ rc = bdev_dax_pgoff(bdev, sector, size, &pgoff);
+ if (rc)
+ return rc;
+
+ id = dax_read_lock();
+ rc = dax_direct_access(dax_dev, pgoff, PHYS_PFN(size), &kaddr,
+ &pfn);
+ if (rc < 0) {
+ dax_read_unlock(id);
+ return rc;
+ }
+ clear_pmem(kaddr + offset, size);
+ dax_read_unlock(id);
}
return 0;
}
@@ -982,9 +998,12 @@ static loff_t
dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
struct iomap *iomap)
{
+ struct block_device *bdev = iomap->bdev;
+ struct dax_device *dax_dev = iomap->dax_dev;
struct iov_iter *iter = data;
loff_t end = pos + length, done = 0;
ssize_t ret = 0;
+ int id;

if (iov_iter_rw(iter) == READ) {
end = min(end, i_size_read(inode));
@@ -1009,34 +1028,42 @@ dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
(end - 1) >> PAGE_SHIFT);
}

+ id = dax_read_lock();
while (pos < end) {
unsigned offset = pos & (PAGE_SIZE - 1);
- struct blk_dax_ctl dax = { 0 };
+ const size_t size = ALIGN(length + offset, PAGE_SIZE);
+ const sector_t sector = dax_iomap_sector(iomap, pos);
ssize_t map_len;
+ pgoff_t pgoff;
+ void *kaddr;
+ pfn_t pfn;

if (fatal_signal_pending(current)) {
ret = -EINTR;
break;
}

- dax.sector = dax_iomap_sector(iomap, pos);
- dax.size = (length + offset + PAGE_SIZE - 1) & PAGE_MASK;
- map_len = dax_map_atomic(iomap->bdev, &dax);
+ ret = bdev_dax_pgoff(bdev, sector, size, &pgoff);
+ if (ret)
+ break;
+
+ map_len = dax_direct_access(dax_dev, pgoff, PHYS_PFN(size),
+ &kaddr, &pfn);
if (map_len < 0) {
ret = map_len;
break;
}

- dax.addr += offset;
+ map_len = PFN_PHYS(map_len);
+ kaddr += offset;
map_len -= offset;
if (map_len > end - pos)
map_len = end - pos;

if (iov_iter_rw(iter) == WRITE)
- map_len = copy_from_iter_pmem(dax.addr, map_len, iter);
+ map_len = copy_from_iter_pmem(kaddr, map_len, iter);
else
- map_len = copy_to_iter(dax.addr, map_len, iter);
- dax_unmap_atomic(iomap->bdev, &dax);
+ map_len = copy_to_iter(kaddr, map_len, iter);
if (map_len <= 0) {
ret = map_len ? map_len : -EFAULT;
break;
@@ -1046,6 +1073,7 @@ dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
length -= map_len;
done += map_len;
}
+ dax_read_unlock(id);

return done ? done : ret;
}
@@ -1152,8 +1180,8 @@ static int dax_iomap_pte_fault(struct vm_fault *vmf,
clear_user_highpage(vmf->cow_page, vaddr);
break;
case IOMAP_MAPPED:
- error = copy_user_dax(iomap.bdev, sector, PAGE_SIZE,
- vmf->cow_page, vaddr);
+ error = copy_user_dax(iomap.bdev, iomap.dax_dev,
+ sector, PAGE_SIZE, vmf->cow_page, vaddr);
break;
default:
WARN_ON_ONCE(1);
@@ -1178,8 +1206,8 @@ static int dax_iomap_pte_fault(struct vm_fault *vmf,
mem_cgroup_count_vm_event(vmf->vma->vm_mm, PGMAJFAULT);
major = VM_FAULT_MAJOR;
}
- error = dax_insert_mapping(mapping, iomap.bdev, sector,
- PAGE_SIZE, &entry, vmf->vma, vmf);
+ error = dax_insert_mapping(mapping, iomap.bdev, iomap.dax_dev,
+ sector, PAGE_SIZE, &entry, vmf->vma, vmf);
/* -EBUSY is fine, somebody else faulted on the same PTE */
if (error == -EBUSY)
error = 0;
@@ -1229,41 +1257,48 @@ static int dax_pmd_insert_mapping(struct vm_fault *vmf, struct iomap *iomap,
loff_t pos, void **entryp)
{
struct address_space *mapping = vmf->vma->vm_file->f_mapping;
+ const sector_t sector = dax_iomap_sector(iomap, pos);
+ struct dax_device *dax_dev = iomap->dax_dev;
struct block_device *bdev = iomap->bdev;
struct inode *inode = mapping->host;
- struct blk_dax_ctl dax = {
- .sector = dax_iomap_sector(iomap, pos),
- .size = PMD_SIZE,
- };
- long length = dax_map_atomic(bdev, &dax);
- void *ret = NULL;
-
- if (length < 0) /* dax_map_atomic() failed */
+ const size_t size = PMD_SIZE;
+ void *ret = NULL, *kaddr;
+ long length = 0;
+ pgoff_t pgoff;
+ pfn_t pfn;
+ int id;
+
+ if (bdev_dax_pgoff(bdev, sector, size, &pgoff) != 0)
goto fallback;
- if (length < PMD_SIZE)
- goto unmap_fallback;
- if (pfn_t_to_pfn(dax.pfn) & PG_PMD_COLOUR)
- goto unmap_fallback;
- if (!pfn_t_devmap(dax.pfn))
- goto unmap_fallback;
-
- dax_unmap_atomic(bdev, &dax);

- ret = dax_insert_mapping_entry(mapping, vmf, *entryp, dax.sector,
+ id = dax_read_lock();
+ length = dax_direct_access(dax_dev, pgoff, PHYS_PFN(size), &kaddr, &pfn);
+ if (length < 0)
+ goto unlock_fallback;
+ length = PFN_PHYS(length);
+
+ if (length < size)
+ goto unlock_fallback;
+ if (pfn_t_to_pfn(pfn) & PG_PMD_COLOUR)
+ goto unlock_fallback;
+ if (!pfn_t_devmap(pfn))
+ goto unlock_fallback;
+ dax_read_unlock(id);
+
+ ret = dax_insert_mapping_entry(mapping, vmf, *entryp, sector,
RADIX_DAX_PMD);
if (IS_ERR(ret))
goto fallback;
*entryp = ret;

- trace_dax_pmd_insert_mapping(inode, vmf, length, dax.pfn, ret);
+ trace_dax_pmd_insert_mapping(inode, vmf, length, pfn, ret);
return vmf_insert_pfn_pmd(vmf->vma, vmf->address, vmf->pmd,
- dax.pfn, vmf->flags & FAULT_FLAG_WRITE);
+ pfn, vmf->flags & FAULT_FLAG_WRITE);

- unmap_fallback:
- dax_unmap_atomic(bdev, &dax);
+unlock_fallback:
+ dax_read_unlock(id);
fallback:
- trace_dax_pmd_insert_mapping_fallback(inode, vmf, length,
- dax.pfn, ret);
+ trace_dax_pmd_insert_mapping_fallback(inode, vmf, length, pfn, ret);
return VM_FAULT_FALLBACK;
}

diff --git a/fs/iomap.c b/fs/iomap.c
index 141c3cd55a8b..4ec0d6ac8bc1 100644
--- a/fs/iomap.c
+++ b/fs/iomap.c
@@ -360,7 +360,8 @@ static int iomap_dax_zero(loff_t pos, unsigned offset, unsigned bytes,
sector_t sector = iomap->blkno +
(((pos & ~(PAGE_SIZE - 1)) - iomap->offset) >> 9);

- return __dax_zero_page_range(iomap->bdev, sector, offset, bytes);
+ return __dax_zero_page_range(iomap->bdev, iomap->dax_dev, sector,
+ offset, bytes);
}

static loff_t
diff --git a/include/linux/dax.h b/include/linux/dax.h
index 0d0d890f9186..d3158e74a59e 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -70,11 +70,13 @@ void dax_wake_mapping_entry_waiter(struct address_space *mapping,
pgoff_t index, void *entry, bool wake_all);

#ifdef CONFIG_FS_DAX
-int __dax_zero_page_range(struct block_device *bdev, sector_t sector,
+int __dax_zero_page_range(struct block_device *bdev,
+ struct dax_device *dax_dev, sector_t sector,
unsigned int offset, unsigned int length);
#else
static inline int __dax_zero_page_range(struct block_device *bdev,
- sector_t sector, unsigned int offset, unsigned int length)
+ struct dax_device *dax_dev, sector_t sector,
+ unsigned int offset, unsigned int length)
{
return -ENXIO;
}